[drallan]

2004 v8 SR5

Been getting a P0440 / P0442 for a while now. Tried replacing gas cap multiple times (including OEM), gaskets, etc. and they keep coming back. Noticed that the little flap in the filler neck isn't there anymore. Not sure when or how it broke, if it is down in the tank or spring just broke. But I recall and from other vehicles, that there is typically some sort of spring loaded flap that covers the fill hole that the gas nozzle pushes out of the way.

Could this be causing my codes? If so, is there an easy way to replace just this part of the filler neck (top metal piece). I've tried looking for it but only find the fully fuel fill hose assembly. Was hoping to not have to remove everything to see if this solves the problem.

As a troubleshooting step I was thinking of getting some sort of plug for the filler hole (like boat drain plug) and stopping it up between fill-ups to see if this solves the problem. Any thoughts on that? I'm not sure how much pressure the standard design lets vent or if there would be any concerns of pressure buildup or vacuum issues.

[MikeinNH67]

All that flapper is for is fuel theft deterrent. It won't fix your code. Anytime I've had a leaking filler neck I was able to smell gas fumes in the area. May be best to have someone put a smoke machine on it.